The objectives of this proposal are to characterize fat digestion and absorption in suckling rats. In particular we propose to isolate and characterize two important and little studied lipolytic enzymes involved in neonatal digestion and absorption of milk triglycerides viz lingual lipase and a bile salt stimulated lipase from pancreas. Since these are both soluble enzymes conventional procedures will be applied as well as preparative isoelectric focusing and affinity chromatography. In the case of lingual lipase we will be concerned with the specificity of the enzyme both with regard to which position of the milk triglyceride it attacks and whether it shows any specificity for the type of fatty acid hydrolyzed from the milk triglyceride. In the case of the bile salt stimulated lipase specificity studies and the stimulatng effect of bile salts will be investigated. In vivo studies will be concerned with the route of absorption of medium chain fatty acids as a function of the position in the triglyceride. In addition, we will test the hypothesis that intact triglycerides are absorbed directly by the mucosal cells. Finally we will isolate and characterize chylomicrons from suckling rat intestinal lymph.